A LCD source driver can have many channels, e.g., 256-1024. The channel-to-channel offset voltage variation is expected to be limited to certain voltage values, e.g., less than +/−5 mV. The channel-to-channel offset voltage variations are tested using various test methods.
Conventional testers for the LCD source driver have drawbacks including increasing testing cost as more channels are tested, or as more accurate analog-to-digital converters (ADC) are used. It is very expensive to use a special mixed-mode (e.g., analog and digital) tester with high-resolution for better accuracy and high pin counts for more channels. Also, testers using a multiplexing switch to share an ADC for the testing require an expensive multiplexing switch, and the testing time is very long, which will increase the testing cost and throughput.
Accordingly, new circuits and methods are desired to solve the above problems.